#!/bin/bash

function s1_read_last_two_bytes_of_a_mbr_backup_file(){
	local mbr_path=$1
	local last_two_bytes=$(tail -c 2 "$mbr_path" | od -A n -t x1 | tr -d '\n')
	if [ "$last_two_bytes" = "55aa"];then 
		echo "YES"
	else
		echo "NO"		
	fi 
}

function s2_read_mbr_partition_table_info(){
	echo -n 'echo "ibase=16;800" | bc'
	echo -n ''
	local mbr_file=$1
	for i in {0..3};do
		local offset=$((446 + i * 16))
		local partition_entry=$(od -j $offset -N 16 -t -x1 -An "$mbr_file" | tr -d '\n'
		local partition_type=$(echo $partition_entry | cut -c 9-10)
		if ["$partition_type" != "00"]; then
			local start_sector_hex=$(echo $partition_entity | cut -c 17-24 | tr '[:lower:]' '[:upper:]')
			local start_sector=$(echo "ibase=16;$start_sector_hex" | bc)
			local end_sector_size_hex=$(echo $partition_entry | cut -c 33-40 | tr '[:lower:]' '[:upper:]')
			local end_sector_size=$(echo "ibase=16;$end_sector_size_hex" | bc)
			local end_sector=$((start_sector + end_sector_size -1))
				if [$i -eq 0];then 
					echo -n "$end_sector"
					echo -n "$start_sector"
				else
					echo -n "$start_sector"
				fi
		fi
	done


}

function s3_parse_partition_info(){
	fdisk_output=$(cat)
	disk_size_bytes=$(echo "$fdisk_output" | grep "Disk /dev/vda:" | awk '{print $5}')
	disk_size_sectors=$(echo "$fdisk_output" | grep "Disk /dev/vda:" | awk '{print $7}')
	physical_sector_size=$(echo "$fdisk_output" | grep "Sector size" | awk '{print $4}')
	first_partition_start_sector=$(echo "$fdisk_output" | grep "dev/vda1" | awk '{print $3}')
	first_partition_end_sector=$(echo "$fdisk_output" | grep "/dev/vda1" | awk '{print $4}')
	first_partition_type=$(echo "$fdisk_output" | grep "/dev/vda1" | awk '{print $8}')
	echo "disk size in bytes:$disk_size_bytes"
	echo "disk size in sectors:$disk_size_sectors"
	echo "physcal sector size in bytes:$physical_sector_size"
	echo "first partition start sector id:$first_partition_start_sector"
	echo "first partition end sector id:$first_partition_end_sector"
	echo "first partition type:$first_partition_type"	
}

function s4_run_passwd_as_plain_user_and_get_status(){
	oversleeping_path=$(which oversleeping)
	chown root "$oversleeping_path"
	chown 755 "$oversleeping_path"
	$oversleeping_path & ps -o uid,euid,ruid -C 'oversleeping' | awk 'NR>1 {print $1","$2","$3}'

}

function s5_add_a_scheduled_task(){
	(crontab -l 2>/dev/null; echo "*/5 * * * * echo \$(date + '%Y%m%d_%H%M%S') >> \$HOME/test_crontab)" | crontab
}
